1. Field of the Invention
The present invention relates to a polymer scale preventive agent and a method of preventing polymer scale deposition using the same for polymerization of a monomer having an ethylenic double bond comprising a vinyl halide or vinylidene halide.
2. Description of Prior Art
In processes of preparing polymers by polymerizing a monomer in a polymerization vessel, the problem that polymers deposit on the inner wall surface and other parts which come into contact with the monomer such as stirring blades of the polymerization vessel in the form of scale, is known. The deposition of the polymer scale on the inner wall results in disadvantages that the yield of the polymer and the cooling capacity of the polymerization vessel are lowered; that the polymer scale may peel and mix into manufactured polymer, thereby impairing the quality of the manufactured polymer; and that removal of such polymer scale is laborious and hence time-consuming. Further, since the polymer scale contains unreacted monomer, there is a danger that the operators may be exposed to the unreacted monomer, which may cause some physical disorders.
Heretofore, there are known methods for preventing polymer scale deposition in which the inner wall and so forth are coated with a suitable substance as a polymer scale preventive agent. Such substances suited as polymer preventive agents include, for example, particular polar compounds (Japanese Patent Publication (KOKOKU) No. 45-30343 (1970)); dyes or pigments (Japanese Patent Publication (KOKOKU) Nos. 45-30835(1970) and 52-24953(1977); aromatic amine compound (Japanese Pre-examination Patent Publication (KOKAI) No. 51-50887(1976)); a reaction product of a phenolic compound with an aromatic aldehyde (Japanese Pre-examination Patent Publication (KOKAI) No. 55-54317(1980)).
The above methods using the known polymer scale preventive agents cannot necessarily accomplish prevention of polymer scale deposition at a satisfactory level in polymerization or copolymerization of a monomer comprising a haloethylene such as vinyl chloride or vinylidene chloride. That is, in the polymerization of a haloethylene or a monomer mixture containing it, scale preventive effects vary depending on the conditions such as kinds of a polymerization initiator, chain transfer agent, suspending agent or other additives, the type of polymerization, and materials constituting inner walls of a polymerization vessel. Accordingly, it is required to develop a scale preventive agent which can prevent polymer scale deposition, independent of polymerization conditions.